However, he says the Health service will learn lessons from the treatment of an elderly man who waited for hours at John Hunter hospital with a fractured skull and left undiagnosed.

The State Opposition says the case of the Mayfield man, who waited in freezing conditions for up to 10 hours and was eventually sent home, proves the hospital's emergency department is under-resourced.

Mr DiRienzo has passed on his apologies to the man and his family, and says they are due to meet hospital managers today to further discuss his case.

But, Mr DiRienzo says it was a busy day in the emergency department.

"Now I don't want to make excuses, but unfortunately on that day, we had a significant number of cardiac arrests and other trauma coming through.

"One of things we need to realise is the John Hunter is a major trauma centre.

"On that particular occasion resources were available throughout the shift but priority was given to those traumas and life-threatening cases that came through."

Free trade is the oldest argument in federal politics and the issue that literally defined the federation era but opposition exists to the TPP, courtesy of the Investor-State Dispute Resolutions clause.